Increasingly sophisticated laboratory equipment and analyses create the need for a ready supply of laboratory grade ultrapure water that is used in such laboratory methods as high performance liquid chromatography, gas chromatography, trace metal analysis by atomic absorption spectrometry, tissue culturing and the like.
Most impurities in potable water are in the form of ionized inorganic mineral salts that lend a degree of conductivity/resistivity to the water and thus render the water susceptible to precise measurement of its purity. The most common measure is by specific resistance, typically measured in units of ohmxc2x7cm at a reference temperature of 25xc2x0 C.; absolutely pure water has a theoretical specific resistance of 18.17 megohmxc2x7cm.
A minority of the impurities in potable water comprise organic contaminants which do not typically bear an ionic charge. Accordingly, such organic contaminants are not measurable in the same fashion as are inorganic impurities. A preferred level of total organic content (TOC) in ultrapure laboratory grade water is no more than a few parts per billion (ppb).
There is an ongoing need to provide laboratory grade ultrapure water on a short term, real time basis, preferably from a supply located in the very laboratory where the research and analysis work is being conducted. This need is met by the present invention, which is summarized and described in detail below.
The present invention comprises a system for the production of laboratory grade ultrapure water utilizing a unique combination of purification media contained in a series of dual housings and preferably coupled with ultraviolet (UV) and ultrafiltration (UF) treatment and a novel arrangement of dispensing, solenoid valves, check valves and sensor devices.